There is conventionally used a method for allowing a terminating mobile switching center (MSC) to provide a uniform ring back tone to a caller when the caller tries to make a telephone call in an existing mobile communication network. However, since the conventional method uniformly provides the same ringing tone, the caller cannot determine the existence of a wrong connection until a called party makes a response.
There has been recently proposed a method for providing advertising jingles in place of the uniform ring back tone. The proposed method provides a specified advertising jingle selected by a communication network provider to a subscriber. At this time, the subscriber is not entitled to select a desired advertising jingle. Where the subscriber hears the specified advertising jingle, the communication network provider provides a predetermined free tall time to the caller. The proposed method also has a problem that the caller cannot determine the existence of a wrong connection until a called party makes a response. Furthermore, the proposed method has another problem that various ring back tones desired by the subscriber cannot be provided.
To address the above-described problems, methods for providing a subscriber-based ring-back-tone service which services, to the caller, a specified sound registered or selected by the called subscriber in place of an existing ring back tone, have been previously proposed by the applicant of the present invention. The previously proposed methods will be described with reference to FIGS. 1 and 2.
FIG. 1 is a flowchart illustrating a method for providing the subscriber-based ling-back-tone service using a terminating mobile switching center (MSC) previously proposed by the applicant of the present invention. This method is disclosed in Korean Patent Application No. 2002-0010006 filed on Feb. 25, 2002.
First, if an arbitrary caller sends a call connection request to a service subscriber (hereinafter, referred to as a “called subscriber”) using the caller's terminal (hereinafter, referred to as a “calling terminal”), a corresponding originating MSC (O_MSC) 31 requests that a home location register (HLR) 10 provide destination location information (S101).
In response to the destination location information request, the HLR 10 requests that a terminating MSC (T_MSC) 32 provide routing information (S102). The T_MSC 32 provides, to the HLR 10, the routing information, i.e., a temporary local directory number (TLDN), as a response to the request (S103).
The HLR 10 makes a response to the destination location information request contained at the above step S101 by sending the routing information to the O_MSC 31 (S104). Then, the O_MSC 31 sends an ISDN User Part (ISUP) call connection request to the T_MSC 32 on the basis of the routing information and then establishes a communication path between the O_MSC 31 and the T_MSC 32(S105).
If the T_MSC 32 receives location information of a corresponding called terminal from the HLR 10 when registering the location information of the corresponding called terminal therein, and then determines that the called terminal corresponds to a service subscriber and is in a service activation state on the basis of service setting information and routing information to be routed to an intellectual peripheral (IP) 50 previously stored in its own device (or a visitor location register (VLR)), the T_MSC 32 sends the ISUP call connection request to the IP 50, establishes a trunk communication path between the T_MSC 32 and the IP 50 and provides originating and terminating telephone numbers to the IP 50 (S106). As a result, a common communication path is established between the O_MSC 31, the T_MSC 32 and the IP 50. For reference, the service setting information and routing information are contained in a location registration response message that is sent from the HLR 10 to the T_MSC 32 when the location information of the corresponding called terminal is registered.
On the basis of the originating and terminating telephone numbers, the IP 50 requests that an IP server 70 provide a sound code (S107). In response to the request, the IP server 70 searches for the sound code linked to the received originating and terminating telephone numbers and transfers the searched sound code to make a response to the request contained at the above step S107 (S108). The IP 50 sends a replacement sound corresponding to the transferred sound code to the calling terminal through the established communication path in place of a ring back tone (S109).
If the called subscriber receives a telephone call while the replacement sound is transferred in place of the ring back tone, the T_MSC 32 recognizes the fact that the called subscriber has received the telephone call, and sends an ISUP call release request to the IP 50 so that the IP 50 can release an ISUP call (S110). Simultaneously, communication between the caller and the called subscriber is performed over the communication path between the O_MSC 31 and the T_MSC 32 (S111).
FIG. 2 is a flowchart illustrating a method for providing the subscriber-based ring-back-tone service using an originating mobile switching center (MSC) previously proposed by the applicant of the present invention. This method is disclosed in Korean Patent Application No. 2002-0047212 filed on Aug. 9, 2002.
First, if an arbitrary caller sends a call connection request to a terminal (or called terminal) of a service subscriber hereinafter, referred to as a “called subscriber”) using the caller's terminal (hereinafter, referred to as a “calling terminal”), a corresponding originating MSC (O_MSC) 31 requests that a home location register (HLR) 10 provide destination location information (S201).
In response to the destination location information request, the HLR 10 requests that a terminating MSC (T_MSC) 32 provide routing information (S202). The T-MSC 32 provides, to the HLR 10, the routing information, i.e., a temporary local directory number (TLDN), as a response to the request (S203).
The HLR 10 makes a response to the destination location information request contained at the above step S201 by sending the routing information to the O_MSC 31. When making the response, the HLR 10 confirms a subscriber profile and determines whether a corresponding called party is a service subscriber, i.e., whether the called terminal is subscribed to the service (S204).
If the corresponding called party is not a service subscriber, the HLR 10 contains only the TLDN within a response message to the destination location information request, and sends the response message to the O_MSC 31 (S205-1). On the other hand, if the corresponding called party is the service subscriber, the HLR 10 contains service setting information and routing information (e.g., routing digits used for routing information to an intellectual peripheral (IP) 50) to be routed to the IP 50 within the response message, and sends the response message to the O_MSC 31 (S205-2).
In response to the response message from the HLR 10 according to a result of the performance of the above step S205-1 or S205-2, the O_MSC 31 sends a trunk (or ISUP) call connection request to only the T-MSC 32 and then establishes a communication path between the O_MSC 31 and the T_MSC 32 (S206). At this time, the O_MSC 31 selectively sends the ISUP call connection request to the IP 50 and then establishes a communication path between the O_MSC 31 and the IP 50 (S207).
If the communication path has been established between the O_MSC 31 and the IP 50 at the above step S207, the IP 50 requests an IP server 70 to provide a sound code on the basis of originating and terminating telephone numbers (S208). In response to the request, the IP server 70 searches for the sound code linked to received originating and terminating telephone numbers and transfers the searched sound code to make a response to the sound code request contained at the above step S208 (S209). The IP 50 sends a replacement sound corresponding to the transferred sound code to the calling terminal through the established communication path in place of a ring back tone (S210).
If the called terminal receives a telephone call while the replacement sound is transferred in place of the ring back tone, the O_MSC 31 recognizes the fact that the called terminal has received the telephone call and sends an ISUP call release request to the IP 50 so that the IP 50 can release an ISUP call (S211). Simultaneously, communication between a caller and a called subscriber is performed over the communication path between the O_MSC 31 and the T_MSC 32 (S212).
Since the number of service subscribers is small when a service is initially provided, a single IP 50 or a small number of IPs 50 are shared between a plurality of MSCs 31 and 32 that are distributed throughout the nation. However, where the number of service subscribers increases, there is a problem in that trunk resources coupled to the single IP 50 or the small number of IPs 50 are concentratedly and excessively occupied and hence a service disable state can be caused.